1 //===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes the target machine instruction set to the code generator.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_TARGET_TARGETINSTRINFO_H
15 #define LLVM_TARGET_TARGETINSTRINFO_H
17 #include "llvm/Target/TargetInstrDesc.h"
18 #include "llvm/CodeGen/MachineFunction.h"
23 class TargetRegisterClass;
24 class TargetRegisterInfo;
26 class CalleeSavedInfo;
29 class MachineMemOperand;
31 template<class T> class SmallVectorImpl;
34 //---------------------------------------------------------------------------
36 /// TargetInstrInfo - Interface to description of machine instruction set
38 class TargetInstrInfo {
39 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
40 unsigned NumOpcodes; // Number of entries in the desc array
42 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
43 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
45 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
46 virtual ~TargetInstrInfo();
48 // Invariant opcodes: All instruction sets have these as their low opcodes.
56 /// KILL - This instruction is a noop that is used only to adjust the liveness
57 /// of registers. This can be useful when dealing with sub-registers.
60 /// EXTRACT_SUBREG - This instruction takes two operands: a register
61 /// that has subregisters, and a subregister index. It returns the
62 /// extracted subregister value. This is commonly used to implement
63 /// truncation operations on target architectures which support it.
66 /// INSERT_SUBREG - This instruction takes three operands: a register
67 /// that has subregisters, a register providing an insert value, and a
68 /// subregister index. It returns the value of the first register with
69 /// the value of the second register inserted. The first register is
70 /// often defined by an IMPLICIT_DEF, as is commonly used to implement
71 /// anyext operations on target architectures which support it.
74 /// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef.
77 /// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except
78 /// that the first operand is an immediate integer constant. This constant
79 /// is often zero, as is commonly used to implement zext operations on
80 /// target architectures which support it, such as with x86-64 (with
81 /// zext from i32 to i64 via implicit zero-extension).
84 /// COPY_TO_REGCLASS - This instruction is a placeholder for a plain
85 /// register-to-register copy into a specific register class. This is only
86 /// used between instruction selection and MachineInstr creation, before
87 /// virtual registers have been created for all the instructions, and it's
88 /// only needed in cases where the register classes implied by the
89 /// instructions are insufficient. The actual MachineInstrs to perform
90 /// the copy are emitted with the TargetInstrInfo::copyRegToReg hook.
91 COPY_TO_REGCLASS = 10,
93 // DEBUG_VALUE - a mapping of the llvm.dbg.value intrinsic
96 // DEBUG_DECLARE - a mapping of the llvm.dbg.declare intrinsic
100 unsigned getNumOpcodes() const { return NumOpcodes; }
102 /// get - Return the machine instruction descriptor that corresponds to the
103 /// specified instruction opcode.
105 const TargetInstrDesc &get(unsigned Opcode) const {
106 assert(Opcode < NumOpcodes && "Invalid opcode!");
107 return Descriptors[Opcode];
110 /// isTriviallyReMaterializable - Return true if the instruction is trivially
111 /// rematerializable, meaning it has no side effects and requires no operands
112 /// that aren't always available.
113 bool isTriviallyReMaterializable(const MachineInstr *MI,
114 AliasAnalysis *AA = 0) const {
115 return MI->getOpcode() == IMPLICIT_DEF ||
116 (MI->getDesc().isRematerializable() &&
117 (isReallyTriviallyReMaterializable(MI, AA) ||
118 isReallyTriviallyReMaterializableGeneric(MI, AA)));
122 /// isReallyTriviallyReMaterializable - For instructions with opcodes for
123 /// which the M_REMATERIALIZABLE flag is set, this hook lets the target
124 /// specify whether the instruction is actually trivially rematerializable,
125 /// taking into consideration its operands. This predicate must return false
126 /// if the instruction has any side effects other than producing a value, or
127 /// if it requres any address registers that are not always available.
128 virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
129 AliasAnalysis *AA) const {
134 /// isReallyTriviallyReMaterializableGeneric - For instructions with opcodes
135 /// for which the M_REMATERIALIZABLE flag is set and the target hook
136 /// isReallyTriviallyReMaterializable returns false, this function does
137 /// target-independent tests to determine if the instruction is really
138 /// trivially rematerializable.
139 bool isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
140 AliasAnalysis *AA) const;
143 /// isMoveInstr - Return true if the instruction is a register to register
144 /// move and return the source and dest operands and their sub-register
145 /// indices by reference.
146 virtual bool isMoveInstr(const MachineInstr& MI,
147 unsigned& SrcReg, unsigned& DstReg,
148 unsigned& SrcSubIdx, unsigned& DstSubIdx) const {
152 /// isCoalescableInstr - Return true if the instruction is "coalescable". That
153 /// is, it's like a copy where it's legal for the source to overlap the
154 /// destination. e.g. X86::MOVSX64rr32.
155 virtual bool isCoalescableInstr(const MachineInstr &MI, bool &isCopy,
156 unsigned &SrcReg, unsigned &DstReg,
157 unsigned &SrcSubIdx, unsigned &DstSubIdx) const {
158 if (isMoveInstr(MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
165 /// isIdentityCopy - Return true if the instruction is a copy (or
166 /// extract_subreg, insert_subreg, subreg_to_reg) where the source and
167 /// destination registers are the same.
168 bool isIdentityCopy(const MachineInstr &MI) const {
169 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
170 if (isMoveInstr(MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
174 if (MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG &&
175 MI.getOperand(0).getReg() == MI.getOperand(1).getReg())
178 if ((MI.getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
179 MI.getOpcode() == TargetInstrInfo::SUBREG_TO_REG) &&
180 MI.getOperand(0).getReg() == MI.getOperand(2).getReg())
185 /// isLoadFromStackSlot - If the specified machine instruction is a direct
186 /// load from a stack slot, return the virtual or physical register number of
187 /// the destination along with the FrameIndex of the loaded stack slot. If
188 /// not, return 0. This predicate must return 0 if the instruction has
189 /// any side effects other than loading from the stack slot.
190 virtual unsigned isLoadFromStackSlot(const MachineInstr *MI,
191 int &FrameIndex) const {
195 /// isLoadFromStackSlotPostFE - Check for post-frame ptr elimination
196 /// stack locations as well. This uses a heuristic so it isn't
197 /// reliable for correctness.
198 virtual unsigned isLoadFromStackSlotPostFE(const MachineInstr *MI,
199 int &FrameIndex) const {
203 /// hasLoadFromStackSlot - If the specified machine instruction has
204 /// a load from a stack slot, return true along with the FrameIndex
205 /// of the loaded stack slot and the machine mem operand containing
206 /// the reference. If not, return false. Unlike
207 /// isLoadFromStackSlot, this returns true for any instructions that
208 /// loads from the stack. This is just a hint, as some cases may be
210 virtual bool hasLoadFromStackSlot(const MachineInstr *MI,
211 const MachineMemOperand *&MMO,
212 int &FrameIndex) const {
216 /// isStoreToStackSlot - If the specified machine instruction is a direct
217 /// store to a stack slot, return the virtual or physical register number of
218 /// the source reg along with the FrameIndex of the loaded stack slot. If
219 /// not, return 0. This predicate must return 0 if the instruction has
220 /// any side effects other than storing to the stack slot.
221 virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
222 int &FrameIndex) const {
226 /// isStoreToStackSlotPostFE - Check for post-frame ptr elimination
227 /// stack locations as well. This uses a heuristic so it isn't
228 /// reliable for correctness.
229 virtual unsigned isStoreToStackSlotPostFE(const MachineInstr *MI,
230 int &FrameIndex) const {
234 /// hasStoreToStackSlot - If the specified machine instruction has a
235 /// store to a stack slot, return true along with the FrameIndex of
236 /// the loaded stack slot and the machine mem operand containing the
237 /// reference. If not, return false. Unlike isStoreToStackSlot,
238 /// this returns true for any instructions that loads from the
239 /// stack. This is just a hint, as some cases may be missed.
240 virtual bool hasStoreToStackSlot(const MachineInstr *MI,
241 const MachineMemOperand *&MMO,
242 int &FrameIndex) const {
246 /// reMaterialize - Re-issue the specified 'original' instruction at the
247 /// specific location targeting a new destination register.
248 virtual void reMaterialize(MachineBasicBlock &MBB,
249 MachineBasicBlock::iterator MI,
250 unsigned DestReg, unsigned SubIdx,
251 const MachineInstr *Orig,
252 const TargetRegisterInfo *TRI) const = 0;
254 /// duplicate - Create a duplicate of the Orig instruction in MF. This is like
255 /// MachineFunction::CloneMachineInstr(), but the target may update operands
256 /// that are required to be unique.
258 /// The instruction must be duplicable as indicated by isNotDuplicable().
259 virtual MachineInstr *duplicate(MachineInstr *Orig,
260 MachineFunction &MF) const = 0;
262 /// convertToThreeAddress - This method must be implemented by targets that
263 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
264 /// may be able to convert a two-address instruction into one or more true
265 /// three-address instructions on demand. This allows the X86 target (for
266 /// example) to convert ADD and SHL instructions into LEA instructions if they
267 /// would require register copies due to two-addressness.
269 /// This method returns a null pointer if the transformation cannot be
270 /// performed, otherwise it returns the last new instruction.
272 virtual MachineInstr *
273 convertToThreeAddress(MachineFunction::iterator &MFI,
274 MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
278 /// commuteInstruction - If a target has any instructions that are commutable,
279 /// but require converting to a different instruction or making non-trivial
280 /// changes to commute them, this method can overloaded to do this. The
281 /// default implementation of this method simply swaps the first two operands
282 /// of MI and returns it.
284 /// If a target wants to make more aggressive changes, they can construct and
285 /// return a new machine instruction. If an instruction cannot commute, it
286 /// can also return null.
288 /// If NewMI is true, then a new machine instruction must be created.
290 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
291 bool NewMI = false) const = 0;
293 /// findCommutedOpIndices - If specified MI is commutable, return the two
294 /// operand indices that would swap value. Return true if the instruction
295 /// is not in a form which this routine understands.
296 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
297 unsigned &SrcOpIdx2) const = 0;
299 /// isIdentical - Return true if two instructions are identical. This differs
300 /// from MachineInstr::isIdenticalTo() in that it does not require the
301 /// virtual destination registers to be the same. This is used by MachineLICM
302 /// and other MI passes to perform CSE.
303 virtual bool isIdentical(const MachineInstr *MI,
304 const MachineInstr *Other,
305 const MachineRegisterInfo *MRI) const = 0;
307 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
308 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
309 /// implemented for a target). Upon success, this returns false and returns
310 /// with the following information in various cases:
312 /// 1. If this block ends with no branches (it just falls through to its succ)
313 /// just return false, leaving TBB/FBB null.
314 /// 2. If this block ends with only an unconditional branch, it sets TBB to be
315 /// the destination block.
316 /// 3. If this block ends with a conditional branch and it falls through to a
317 /// successor block, it sets TBB to be the branch destination block and a
318 /// list of operands that evaluate the condition. These operands can be
319 /// passed to other TargetInstrInfo methods to create new branches.
320 /// 4. If this block ends with a conditional branch followed by an
321 /// unconditional branch, it returns the 'true' destination in TBB, the
322 /// 'false' destination in FBB, and a list of operands that evaluate the
323 /// condition. These operands can be passed to other TargetInstrInfo
324 /// methods to create new branches.
326 /// Note that RemoveBranch and InsertBranch must be implemented to support
327 /// cases where this method returns success.
329 /// If AllowModify is true, then this routine is allowed to modify the basic
330 /// block (e.g. delete instructions after the unconditional branch).
332 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
333 MachineBasicBlock *&FBB,
334 SmallVectorImpl<MachineOperand> &Cond,
335 bool AllowModify = false) const {
339 /// RemoveBranch - Remove the branching code at the end of the specific MBB.
340 /// This is only invoked in cases where AnalyzeBranch returns success. It
341 /// returns the number of instructions that were removed.
342 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
343 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
347 /// InsertBranch - Insert branch code into the end of the specified
348 /// MachineBasicBlock. The operands to this method are the same as those
349 /// returned by AnalyzeBranch. This is only invoked in cases where
350 /// AnalyzeBranch returns success. It returns the number of instructions
353 /// It is also invoked by tail merging to add unconditional branches in
354 /// cases where AnalyzeBranch doesn't apply because there was no original
355 /// branch to analyze. At least this much must be implemented, else tail
356 /// merging needs to be disabled.
357 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
358 MachineBasicBlock *FBB,
359 const SmallVectorImpl<MachineOperand> &Cond) const {
360 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
364 /// copyRegToReg - Emit instructions to copy between a pair of registers. It
365 /// returns false if the target does not how to copy between the specified
367 virtual bool copyRegToReg(MachineBasicBlock &MBB,
368 MachineBasicBlock::iterator MI,
369 unsigned DestReg, unsigned SrcReg,
370 const TargetRegisterClass *DestRC,
371 const TargetRegisterClass *SrcRC) const {
372 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
376 /// storeRegToStackSlot - Store the specified register of the given register
377 /// class to the specified stack frame index. The store instruction is to be
378 /// added to the given machine basic block before the specified machine
379 /// instruction. If isKill is true, the register operand is the last use and
380 /// must be marked kill.
381 virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
382 MachineBasicBlock::iterator MI,
383 unsigned SrcReg, bool isKill, int FrameIndex,
384 const TargetRegisterClass *RC) const {
385 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
388 /// loadRegFromStackSlot - Load the specified register of the given register
389 /// class from the specified stack frame index. The load instruction is to be
390 /// added to the given machine basic block before the specified machine
392 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
393 MachineBasicBlock::iterator MI,
394 unsigned DestReg, int FrameIndex,
395 const TargetRegisterClass *RC) const {
396 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
399 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
400 /// saved registers and returns true if it isn't possible / profitable to do
401 /// so by issuing a series of store instructions via
402 /// storeRegToStackSlot(). Returns false otherwise.
403 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
404 MachineBasicBlock::iterator MI,
405 const std::vector<CalleeSavedInfo> &CSI) const {
409 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
410 /// saved registers and returns true if it isn't possible / profitable to do
411 /// so by issuing a series of load instructions via loadRegToStackSlot().
412 /// Returns false otherwise.
413 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
414 MachineBasicBlock::iterator MI,
415 const std::vector<CalleeSavedInfo> &CSI) const {
419 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack
420 /// slot into the specified machine instruction for the specified operand(s).
421 /// If this is possible, a new instruction is returned with the specified
422 /// operand folded, otherwise NULL is returned. The client is responsible for
423 /// removing the old instruction and adding the new one in the instruction
425 MachineInstr* foldMemoryOperand(MachineFunction &MF,
427 const SmallVectorImpl<unsigned> &Ops,
428 int FrameIndex) const;
430 /// foldMemoryOperand - Same as the previous version except it allows folding
431 /// of any load and store from / to any address, not just from a specific
433 MachineInstr* foldMemoryOperand(MachineFunction &MF,
435 const SmallVectorImpl<unsigned> &Ops,
436 MachineInstr* LoadMI) const;
439 /// foldMemoryOperandImpl - Target-dependent implementation for
440 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
441 /// take care of adding a MachineMemOperand to the newly created instruction.
442 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
444 const SmallVectorImpl<unsigned> &Ops,
445 int FrameIndex) const {
449 /// foldMemoryOperandImpl - Target-dependent implementation for
450 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
451 /// take care of adding a MachineMemOperand to the newly created instruction.
452 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
454 const SmallVectorImpl<unsigned> &Ops,
455 MachineInstr* LoadMI) const {
460 /// canFoldMemoryOperand - Returns true for the specified load / store if
461 /// folding is possible.
463 bool canFoldMemoryOperand(const MachineInstr *MI,
464 const SmallVectorImpl<unsigned> &Ops) const {
468 /// unfoldMemoryOperand - Separate a single instruction which folded a load or
469 /// a store or a load and a store into two or more instruction. If this is
470 /// possible, returns true as well as the new instructions by reference.
471 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
472 unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
473 SmallVectorImpl<MachineInstr*> &NewMIs) const{
477 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
478 SmallVectorImpl<SDNode*> &NewNodes) const {
482 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
483 /// instruction after load / store are unfolded from an instruction of the
484 /// specified opcode. It returns zero if the specified unfolding is not
485 /// possible. If LoadRegIndex is non-null, it is filled in with the operand
486 /// index of the operand which will hold the register holding the loaded
488 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
489 bool UnfoldLoad, bool UnfoldStore,
490 unsigned *LoadRegIndex = 0) const {
494 /// ReverseBranchCondition - Reverses the branch condition of the specified
495 /// condition list, returning false on success and true if it cannot be
498 bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
502 /// insertNoop - Insert a noop into the instruction stream at the specified
504 virtual void insertNoop(MachineBasicBlock &MBB,
505 MachineBasicBlock::iterator MI) const;
507 /// isPredicated - Returns true if the instruction is already predicated.
509 virtual bool isPredicated(const MachineInstr *MI) const {
513 /// isUnpredicatedTerminator - Returns true if the instruction is a
514 /// terminator instruction that has not been predicated.
515 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
517 /// PredicateInstruction - Convert the instruction into a predicated
518 /// instruction. It returns true if the operation was successful.
520 bool PredicateInstruction(MachineInstr *MI,
521 const SmallVectorImpl<MachineOperand> &Pred) const = 0;
523 /// SubsumesPredicate - Returns true if the first specified predicate
524 /// subsumes the second, e.g. GE subsumes GT.
526 bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
527 const SmallVectorImpl<MachineOperand> &Pred2) const {
531 /// DefinesPredicate - If the specified instruction defines any predicate
532 /// or condition code register(s) used for predication, returns true as well
533 /// as the definition predicate(s) by reference.
534 virtual bool DefinesPredicate(MachineInstr *MI,
535 std::vector<MachineOperand> &Pred) const {
539 /// isPredicable - Return true if the specified instruction can be predicated.
540 /// By default, this returns true for every instruction with a
541 /// PredicateOperand.
542 virtual bool isPredicable(MachineInstr *MI) const {
543 return MI->getDesc().isPredicable();
546 /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
547 /// instruction that defines the specified register class.
548 virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
552 /// GetInstSize - Returns the size of the specified Instruction.
554 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const {
555 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!");
559 /// GetFunctionSizeInBytes - Returns the size of the specified
562 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0;
564 /// Measure the specified inline asm to determine an approximation of its
566 virtual unsigned getInlineAsmLength(const char *Str,
567 const MCAsmInfo &MAI) const;
570 /// TargetInstrInfoImpl - This is the default implementation of
571 /// TargetInstrInfo, which just provides a couple of default implementations
572 /// for various methods. This separated out because it is implemented in
573 /// libcodegen, not in libtarget.
574 class TargetInstrInfoImpl : public TargetInstrInfo {
576 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
577 : TargetInstrInfo(desc, NumOpcodes) {}
579 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
580 bool NewMI = false) const;
581 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
582 unsigned &SrcOpIdx2) const;
583 virtual bool PredicateInstruction(MachineInstr *MI,
584 const SmallVectorImpl<MachineOperand> &Pred) const;
585 virtual void reMaterialize(MachineBasicBlock &MBB,
586 MachineBasicBlock::iterator MI,
587 unsigned DestReg, unsigned SubReg,
588 const MachineInstr *Orig,
589 const TargetRegisterInfo *TRI) const;
590 virtual MachineInstr *duplicate(MachineInstr *Orig,
591 MachineFunction &MF) const;
592 virtual bool isIdentical(const MachineInstr *MI,
593 const MachineInstr *Other,
594 const MachineRegisterInfo *MRI) const;
596 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const;
599 } // End llvm namespace